Does including entire text of emails bog down the system badly?

We have 5 licenses and 3 sales guys adding info daily to 7,000 contact database. We're considering making the email history default to save text of message (but not attachments) instead of just the subject line. Standard messages from email templates that we know what they say and are long we intend change the option when we send them and just do the Subject LIne.

It'll help sales team communication but I am concerned it will blow up the file to huge...bog down syncs and cause other probs I can't anticipate. Anyone had any experience with this?